Process for treating woods and other porous substances



may 22, 1.923. ,323

' F. H. MCPHERSON ET AL PROCESS FOR TREATING WOODS AND OTHER PORO 'S SUBSTANCES Filed Nov. 28, 1921 BY M ATTORNEY Patented May 22, 1923.

n rr a FLOYD H. MCPHERSON, 0]? LOS ANGELES, AND JOSEPH M. ABRAMS, OF SAN FRANCISCO, CALIFORNIA.

PROCESS FOR TREATING WOODS AND OTHER POROUS SUBSTANCES.

Application filed November 28, 1921.

To aZZ whom it may concern Be it known that we, FLOYD H. MCPHER- SON and Josnrrr M. ABRAMs, citizens of the United States, and residents, respectively, of the city and county of Los Angeles and the city and county of San Francisco, both in the State of California, have invented certain new and useful Improvements in Processes for Treating Woods and Other Porous Substances, of which the following is a specification. 7

Our invention relates to processes for the preservation of woods and other porous substances'such as fabrics for aeroplanes, by means of forcing any high-grade pulverized cement, such as ortland cement in solution, into the pores of the substances.

The objects of our invention are to treat porous substances by our process, producing products impregnated with cement that will be impervious to moisture and thus perm t no passage for general depreciation by the elements. Such products will be rendered more or less fire-proof and also offer great protection against wood-destroying agents common to supporting timbers in the ground or water.

It is also our object to so govern our process-treatment that the full fiber-strength of substances shall be maintained where such strength is necessary.

The principal articles to be treated are construction timbers, rail-road ties, piles, paving-blocks, fence-posts, shingles and small Wooden products, also fabrics and other porous substances that could be beneficially treated for preservation by our process.

The accom anyin drawing to which reference is here y ma e illustrates an apparabus in ide elevation for carrying into effect the process, in which:

1 is a metal receiving tank with preferably a hinged door 2- at each end adapted to be closed and sealed by any approved means,

such as swing-bolts 2 spaced around the edge of the door. 3 is a continuous coil of pipe for steam circulation resting on bracket-su ports 4, the latter being secured to the insi e top of the receiver. The pipecoil is provided with an inlet and valve 5 and an outlet and valve 6 near one end of the receiver, the steam being supplied from any available source.

7 is a suitable vacuum pump with its suction pipe and valve 8 leading to the pipe- Serial No. 518,229.

header 9 which is provided with a control valve 10 and terminates in the receiver at 11. 12 is a suitable air-compressor with its discharge pipe and valve 13 also leading into the header 9. From this header be neath its control valve 10, an over-flow pipe 14 extends with its valve 15. I Below the receiver is a mixing and storage tank 16 provided with a manhole 17 at its top, and at its bottom near one end with an outlet and Valve 18; the tank being positioned on its foundation sloping slightly towards this outlet end. From the latter end a pipe 19 leads to the suction inlet of a centrifugal pump 20 preferably of the sand and gravel type; from its discharge outlet at suitable checlcvalve 21, pipe 22, and shutoff valve 23 lead .0 the bottom of the receiver l at one end.

At the top of the eceiver is a relief valve 24 with its relief outlet connected to a reliefreturn line 25 to the mixing-tank 16. This line is open to theatmosphere at one end and its opposite end leads into adrain line 26 just beneath the valve 27. This latter line is the drain from the receiver to the storage and mixing-tank. The/receiver also slopes towards its drain outlet. At the open end of the relief-return line is a funnel 28 located just under the outlet opening of the over-flow pipe 14. The relief-return line is also provided with a valve 29 and a branch line and valve 39 leading to it from the pipe line 22.

The receiver 1 is provided at its top with a vacuum and pressure gauge 30 and a thermometer 31, and the mixing and storage tank is also provided at its top with a valve 32, a vacuum and pressure gauge 33, a thermometer 34781161 a relief valve 35, and at its bottom with a drain outlet valve 36.

Our process in treating porous materials with this apparatus is as follows: If the timber 37 is seasoned before undergoing our treatment, itis put into the receiver in any advantageous manner and the pieces are spaced apart from each other by thin stri s 38. Part or the entire open space may utilized up to the pipe-coils 3; the doors are then closed and sealed. Valve 15 of the over-flow line is opened and adjacent valve 10 closed.

In the mixing-tank 16 cement and Water are put in through the manhole 17 and mixed until a thin solution results. We prefer to accomplish this mixing throu h the action of the centrifugal pump 20; Talves 23, 29, 27 and 36 are closed and 18 and 39 opened. Pump 20 is then started and the solution flows from the bottom of the mixing-tank through pipe 19 and the pump and back to the mixing-tank at its top through inlet 26. This circulation is continued until the solution is thorou hly mixed and of the desired consistency. nlet valve 23 to the receiver is then opened and valve 39 closed and valve 29 in the relief-return line opened.

circulated through the coils 3. Pump dis-.

charge valve 23 is then closed and the pump stopped. The circulating steam heats the pipecoils which in turn impart heat to the solution causing the latter to expand. As the temperature of the liquid increases, expansion increases and the liquid exerts increasing ressure to the pores of the wood and the epth of penetration of the cement solution into the pores is thus controlled by the temperature of the steam, the quantity of it circulated andthe time duration of the circulation.

Diflerent grades of woods and fabrics require varying temperature and pressure conitions, the object being to so govern the operations that after treatment the fibers of the materials shall retain their full strength. In some cases of timber treatment stren h is not so important, the problem being t at olr; PEOtBCtlOIl against Wood-destroying agents 0 1e y.

As the treatment progresses the pressure and vacuum gauge 30 and thermometer 31 are observed, and when the predetermined pressure and temperature have been reached, together with the length of time required, the steam inlet valve 5 is closed.

The relief valve 24 is always set-at a predetermined pressure to suit requirements and allowed to exhaust into the relief line 25 and to the atmosphere through funnel 28.

The receiver and contents are allowed to cool to partiallyset the cement, but in many cases We. may prefer to drain the receiver before cooling. To drain the receiver, valve 27 in the drainline to the storage and-mixing-tank is opened, also valve 15 in the overflow line for vent. Valve 32 on the manhole cover of the'mixing-tank isalso opened for vent.

The mixing-tank also has its pressure and 1 have been removed and refilled with un-' treated materials.

As the treated materials are removed from the receiver, dry sand is thrown or sifted on each piece to'keep them from sticking together when piled for drying or storage. If the apparatus isnot to be immediately used again, the receiver and pipe 'lines are cleaned and hosed with water.

When green timber is treated the same process is repeated, but an additional preliminary step to dry the timber is necessary, which consists of creating a vacuum in the receiver by means of the vacuum pump 7,

all immediate valves being closed with the exception of valve 10 and valve 8 leading to the vacuum pump. At the same time steam is circulated through the pipe-coil 3 to heat the receiver and its contents.

When the combined heat and vacuum accomplish the drying of the timber, the vacuum pump is stopped and the steam shut 0E and valve 10 closed; then the treatment already described is carried through and in some cases carried further when haste in the settin of the cement-"impregnated products is (lesired. The latter is accomplished by compressed air from the air-compressor 12. Just previous to the draining of the receiver the compressor is started,.

valves 8 and 15 observed to see if closed and 13 and 10 opened, then drain-valve 27 is opened, also valve 32 on the manhole cover of the mixing-tank for vent. The air pressure on the cement solution in the receiver causes it to drain more rapidly than by gravity. The moment the draining is completed valve 27 and valve 32 are closed. The air pressure is continued and allowed to reach a predetermined pressure depending upon the character of the lumber treated, and maintaineda sufiicient length of time to set or partially set the cement. The timbers are then removed and sanded and are ready for use or'storage.

Valve 32 of the mixing-tank is closed in order to keep the tank air-tight to prevent the liquid cement from evaporating or setting should it be desired to keep the liquid cement for some time; otherwise drainvalve 36 is opened and the solution drained oft and the tank flushed out.

At the present time the pressures considered range from below atmosphere to 175 pounds, and the temperature from that of the atmosphere to 250 degrees, and the time for treatment from less than an hour to 10 hours, all depending upon the condition and character of the wood or materials to be treated. For example, redwood shingles are thoroughly treated in less than an hour, while harde'r woods take a much greater length of time.

The apparatus throughout is designed for high pressure and all the valves, pipes,

fittings and power-driven units are suitably.

selected for the functions each is to perform.

Our invention may be subjected to'modifications within the scope of the appended consisting in heating the wood and exhausting the air moisture from the pores thereof, and forcing into the said pores a cement solution and retaining the pressure thereon after thelenveloping cement solution has been drained off until the impregnated cement partially sets, substantially as described.

4. The method of treating porous substances, consisting of exhaustin the air and moisture from the pores thereo and injectment.

-5. The inethod of treatin porous sub-v stances, consisting in filling t e pores or interstices thereof with cement in solution by pressure, and said pressure adapted to be retained thereon until the cement partially sets.

FLOYD H. MQPHERSON. JOSEPH M. ABRAMS. "Witness for FLOYD H. MoPnERsoN:

C. A. WOERNERY H. A. BOND.

35' ing into said exhausted pores a liquid ce' 

